Thermal Conductivity

Thermal Conductivity is the property of a material that determines how quickly it heats or cools as it comes into contact with objects of different temperatures. Although the game states that between two objects, the lowest thermal conductivity is used, this is not true for all cases.

Equations
The calculation of Heat Transfer $$q$$ in $$DTU$$ is mainly a product of:
 * $$\Delta T$$ the Temperature difference in °C
 * $$\Delta t$$ the passing time, which, in any case is one tick is $$0.2s$$
 * $$k$$ the applicable thermal conductivity in $$DTU/(m \cdot s \cdot \text{°}C)$$
 * $$k_{lowest}$$ is the lower of the two
 * $$k_{average}$$ the average of the two: $$0.5 (k_1 + k_2)$$
 * $$k_{geom}$$ is the geometric mean of the two: $$\sqrt{k_1 \cdot k_2}$$
 * as well as additional Factor, like:
 * $$C$$ the real heat capacity $$C = \text{mass} \cdot (\text{specific heat capacity})$$ of the hotter material
 * $$A$$ the buildings area

Any Tiles, be they normal, insulated metal, plastic, bunker, glass or carpeted tiles, as well as doors, Farm Tiles, Heavi-Watt (Conductive) Joint Plates, and Tube Crossings count as Solid Cells, not as buildings. Insulated Tiles reduce the thermal conductivity of their building material by a factor of 100.

Note: in real life, the units would cancel out, but surface area plays no role in ONI's calculation, therefore an additional $$[m]$$ meter needs to be multiplied to the product to have the equation result in DTU. (Not just meter, but a large string of units when calculating buildings.)

Another way to interpret this is that the units of Thermal Conductivity are given in-game as $$DTU/(m \cdot s \cdot \text{°}C)$$ while the unit is actually interpreted as $$DTU/(s \cdot \text{°}C)$$.

Lower Limits
Heat Transfer will not occur if:
 * the temperature difference is less than 1 °C
 * the calculated thermal flow is less than 0.1 DTU
 * either of the masses is less than 1g

Upper limits
Heat Transfer has two caps:
 * If the calculated heat transfer would result in a temperature jump of more than a fourth of their temperature difference $$(T_1-T_2)/4$$ in either material. $$q_{\text{max }1a}=\frac{T_1-T_2}{4}\cdot m_1 \cdot c_1 \quad \text{or}\quad q_{\text{max }1b}=\frac{T_1-T_2}{4}\cdot m_2 \cdot c_2$$ Simply said: if the temperature difference is 40°C, a materials temperature can change at most 10°C per tick
 * If the calculated heat transfer is larger than an eighths of the total heat difference $$(Q_1 - Q_2)/8$$, where the total heat $$Q$$ is a product of its temperature $$T$$, mass $$m$$, and specific heat capacity $$c$$: $$Q= T \cdot m \cdot c$$ $$q_{\text{max }2}=\frac{Q_1-Q_2}{8}=\frac{(T_1 \cdot m_1 \cdot c_1) - (T_2 \cdot m_2 \cdot c_2)}{8}$$

Thermal descriptors
There are 4 thermal descriptors in the game, and they get attached to elements when their thermal characteristic reache a certain threshold. These descriptor does not affect the element any further.
 * Thermally Reactive: Elements have a specific Heat Capacity of less than or equal to 0.2
 * Slow heating: Elements have a specific Heat Capacity of greather than or equal to 1.0
 * Insulator: Elements have a thermal conductivityof less than or equal to 1.0
 * High Thermal Conductivity: Elements have a thermal conductivity of greather than or equal to 10.0

Tips

 * When cooling or heating an area it's better to run pipes through tiles than through atmosphere. in both cases the equation for "Building and the cells it occupies" is used which multiplies both Thermal conductivities, and in general, gasses have a much lower thermal conductivity than liquids, which have lower conductivity than solids.
 * However, if drastic cooling is desired, then Steam Turbines and Aquatuners will have to be involved, which means a cavity filled with Steam will have to be used.
 * To jury rig insulate without building new Insulated tiles, it's therefore better to run pipes through atmosphere and have the pipes therefore changing less heat with the environment.
 * Since Insulated Tiles have a factor of 1/100, and pipes a factor of 1/32, less heat is transfered if a regular pipe goes through an insulated Tile than when an insulated pipe goes through a regular Tile. Though, of course, Insulating both has an even better insulating effect.